This invention relates generally to synthetic fire logs of the type often used as substitutes for natural wood logs in fireplaces, and methods for making the same. More specifically, the invention relates to synthetic fire logs made from, among other things, wood fibers or sawdust and wax.
Generally speaking, such synthetic logs are known and used in the prior art. See, for example, the log and method for making it as disclosed in U.S. Pat. No. 4,179,269 issued to Williard L. Yates on Dec. 18, 1979 wherein approximately 55-80 percent by weight of ground coal is mixed at room temperature with a small quantity of wood fiber ranging up to 10 percent by weight. With this substance is mixed melted slack wax in proportions ranging from 20-35 percent by weight such that a putty-like, extrudable mixture is formed. The latter mixture is then fed to an extruder while at a temperature elevated slightly above normal room temperature by reason of the addition of the melted slack wax, i.e. 80-95 degrees F. whereupon a cylindrical mass is extruded. The extruded mass is then cut to the desired lengths to form logs, the logs are rolled in a flame coloring agent and then wrapped for shipment.
Sawdust, coal dust, and molasses have also long been known as suitable agents for compressed synthetic fire kindlers as disclosed in U.S. Pat. No. 678,346 issued to C. W. Mettler, et al. on July 9, 1901. That patent teaches the saturation of sawdust with petroleum tar after which comminuted coke and powdered soft coal is thoroughly intermixed therewith. Thereafter, a composition consisting of starch and hot water containing 10 percent molasses is added to form a glutinous mass which is then molded under pressure into thin elongate fire kindler tubes. One difficulty encountered with this composition as mentioned in the reference is that care must be taken to thoroughly and equally intermix the components since the molasses and starch must be combined to form a primary binder to hold the tube together until used as a kindler and until burning is under way, after which the starch composition combines with the powdered soft coal to form a secondary binder to hold the mass together until it is completely burned.
In U.S. Pat. No. 734,743 issued to Alfred Paul on July 28, 1903, a fuel consisting of coal dust screenings, 14-15 pounds; wood sawdust, one to one and one-fourth pounds; ground resin, one pound, six ounces to one pound, 10 ounces; sour beer, one-half gallon; and molasses, four to eight ounces is disclosed. The mixture is pressed into form and baked or dried into a hard solid body suitable for use in a fireplace.
Another artificial fuel is disclosed in U.S. Pat. No. 764,526 issued to M. C. Gama, on July 5, 1904 consisting of crude oil; residum of refined oil equal to the quantity of crude oil; tallow, one-tenth to one-fifth of the quantity of the crude oil; sawdust or manure, one-fifth to one-tenth the quantity of the crude oil; coal-dust, one tenth of the quantity of the crude oil; and caustic soda, one-tenth the quantity of the crude oil, all as measured by weight. The composition is then thoroughly mixed and heated in a vessel over an active fire for one or two hours to form a pasty mass, like stiff dough, in which state the fuel is ready for use. One difficulty to be encountered with this composition is the substantial amount of time involved in its heating and drying. Another difficulty is that it forms a pasty mass rather than a secure, stable solid form.
All of the foregoing compositions are believed to be relatively fast burning substances with relatively low BTU output, both disadvantageous features for synthetic fire logs which ideally should be of relatively long burning duration with relatively high BTU output. By means of my invention, as hereinafter described, these and other difficulties encountered using prior art synthetic fire logs are substantially reduced or otherwise overcome.